We calculate the expected signal-to-noise ratio (SNR) for spectral features in the transit spectrum of an Earth-like
exoplanet, for the case of the nearest likely transit of a G and an M star, for a 6-m telescope in space. We find that the
SNR values for all important spectral features, in the visible and infrared, are in the range 0.2 to 1.1, making the
detection of such features difficult.